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  1. What order of reactivity do you predict will be observed when each alkyl halide is mixed with sodium iodide in acetone?

    • 1-Chlorobutane
    • 1-Bromobutane
    • 2-Chloro-2-methylpropane
    • Bromobenzene
    • 2-Chlorobutane
    • 1-Chloro-2-butene

I know that $\ce{I-}$ is the best leaving group, followed by $\ce{Br-}$ and $\ce{Cl-}$.
For the $\ce{NaI}$ reaction, tertiary halides should react fastest and primary halides should react slowest.

  1. What order of reactivity do you predict will b observed when each alkyl halide is mixed with silver nitrate in ethanol?

    • 1-Chlorobutane
    • 1-Bromobutane
    • 2-Chloro-2-methylpropane
    • Bromobenzene
    • 2-Chlorobutane
    • 1-Chloro-2-butene

For the $\ce{AgNO3}$ reaction, primary halides should react fastest and tertiary halides should react slowest.

Which takes preference, leaving group or rank? Also, how do I rank 1-chlorobutane vs. 1-chloro-2-butene? They are both primary and the halide is $\ce{Cl-}$ for both.

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    $\begingroup$ Welcome to chemistry.SE. This is a homework question so please show your thoughts and workings towards a solution because we are not going to just do your homework for you. meta.chemistry.stackexchange.com/questions/141/… $\endgroup$ – bon Mar 23 '15 at 17:59
  • $\begingroup$ possible duplicate - chemistry.stackexchange.com/questions/27734/… $\endgroup$ – Binary Geek Mar 24 '15 at 8:15
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    $\begingroup$ Question one is basically which one does Sn1 fastest (aprotic solvent and strong nucleophile). So in question 1 you're looking for the least substituted species with the best leaving group. Question 2 is basically which one does Sn2 fastest (protic solvent and weak nucleophile). More subbed and better LG. $\endgroup$ – RobChem Mar 24 '15 at 8:41
  • $\begingroup$ For the Chlorobutane/ene situation think about resonance stabilization in the intermediate/transition state. $\endgroup$ – RobChem Mar 24 '15 at 13:20
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  1. Acetone a is aprotic polar solvent which is often used as solvent for $\ce{S_{N}2}$ reactions (notably in conjunction with $\ce{NaI}$ as in the Finkelstein reaction). For $\ce{S_{N}2}$ reactions steric hindrance and leaving group capability is of great importance, so primary halides will be usually easier replaced by iodine then tertiary.

  2. $\ce{AgNO3}$ will probably react as a base forming nitric acid. Even though nitric acid is a rather strong acid this is more likely than $\ce{NO_3-}$ acting as nucleophile. Besides that, $\ce{Ag+}$ is known to have a unique selectivity for halogens and will attack them readily, forming $\ce{AgX}$ and a carbocation, hence promoting $\ce{E 1}$/$\ce{S_{N}1}$.

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